Background: In the context of health care in Belgium, the psychological or psychiatric opinion of a multidisciplinary team is required in the assessment of bariatric surgery candidates. In clinical practice, a wide variety of liaison psychiatry assessment methods exist. Subjects and methods: On the basis of a post-operative psychiatric comorbidity case report and a literature review on "liaison psychiatry and bariatric surgery" we aim to identify opportunities for the systematization of bariatric pre-surgery psychiatric evaluation. Results: The bariatric pre-surgery evaluation must be rigorous and founded on evidence-based medicine. On this basis, specific psychiatric criteria may be defined and researched in assessments. The issue remains for psychiatric comorbidities that develop after surgery and for which a preventive framework should be sustained in the liaison psychiatry approach. Conclusions: The aim of the research is to support an improved systematization of the psychological assessments of preoperative bariatric surgery candidates. We believe that systematic evaluation tools should be defined for the identification of possible absolute or relative contra-indications and that a preventive approach to post-operative psychiatric disorders should be included in this assessment